Low vibration resonant scanning unit for miniature optical display apparatus
First Claim
1. A resonant electromechanical scanning unit comprising;
- a base;
a mirror;
first spring means connecting said mirror to said base so as to allow said mirror to oscillate relative to said base, said mirror and said first spring means forming a first spring/mass system having a first mechanical resonant oscillation frequency and tranferring a first reaction force to said base;
a counterbalance mass;
second spring means connecting said counterbalance mass to said base so as to allow said counterbalance mass to oscillate relative to said base, said counterbalance mass and said second spring means forming a second spring/mass system having a second mechanical resonant oscillation frequency substantially equal to said first mechanical resonant oscillation frequency and transferring a second reaction force to said base; and
driving motor means for imparting motion to at least one of said mirror and said counterbalance mass, said first spring means and said second spring means being connected to said base so that said first reaction force and said second reaction force substantially cancel each other at said base.
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Accused Products
Abstract
A resonant scanning unit utilizes a "tuning fork" design with a mirror mounted on one arm of the tuning fork and a counterbalance mass mounted on the other arm. A voice coil electromagnetic motor mounted between the arms causes the arms to move in opposite directions. Light generated by a line of LEDs is reflected from the oscillating mirror to generate a raster display. Reaction forces generated by the motions of the mirror and counterbalance mass cancel each other at the device base, reducing vibration. In addition, the inventive structure allows placement of the mirror pivot point away from the center of the mirror which allows display devices constructed with the structure to be reduced in size.
192 Citations
26 Claims
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1. A resonant electromechanical scanning unit comprising;
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a base; a mirror; first spring means connecting said mirror to said base so as to allow said mirror to oscillate relative to said base, said mirror and said first spring means forming a first spring/mass system having a first mechanical resonant oscillation frequency and tranferring a first reaction force to said base; a counterbalance mass; second spring means connecting said counterbalance mass to said base so as to allow said counterbalance mass to oscillate relative to said base, said counterbalance mass and said second spring means forming a second spring/mass system having a second mechanical resonant oscillation frequency substantially equal to said first mechanical resonant oscillation frequency and transferring a second reaction force to said base; and driving motor means for imparting motion to at least one of said mirror and said counterbalance mass, said first spring means and said second spring means being connected to said base so that said first reaction force and said second reaction force substantially cancel each other at said base. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A resonant electromechanical scanning unit comprising;
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a base; a mirror; a first spring means connecting said mirror to said base so as to allow said mirror to oscillate about a first pivot point relative to said base, said mirror and said first spring means forming a first spring/mass system having a first mechanical resonant oscillation frequency and tranferring a first reaction force to said base; a counterbalance mass; a second spring means connecting said counterbalance mass to said base so as to allow said counterbalance mass to oscillate about a second pivot point relative to said base, said counterbalance mass and said second spring means forming a second spring/mass system having a second mechanical resonant oscillation frequency substantially equal to said first mechanical resonant oscillation frequency and transferring a second reaction force to said base; and a voice coil driving motor mounted on said mirror and said counterbalance mass for simultaneously imparting opposite motions to said mirror and to said counterbalance mass, said first pivot point being located relative to said second pivot point so that said first reaction force and said second reaction force substantially cancel each other at said base. - View Dependent Claims (10, 11, 12, 13, 14)
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15. A miniature optical display device for generating a raster image to display selected information, said display device comprising:
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a linear array of light-emitting devices; a mirror; an optical system located between said linear array and said mirror, said optical system projecting a virtual image of said linear array via said mirror; a base; first spring means connecting said mirror to said base so as to allow said mirror to oscillate relative to said base, said mirror and said first spring means forming a first spring/mass system having a first mechanical resonant oscillation frequency and imparting a first reaction force to said base; a counterbalance mass; second spring means connecting said counterbalance mass to said base so as to allow said counterbalance mass to oscillate relative to said base, said counterbalance mass and said second spring means forming a second spring/mass system having a second mechanical resonant oscillation frequency substantially equal to said first mechanical resonant oscillation frequency and imparting a second reaction force to said base; and driving motor means for imparting opposite motions to said mirror and to said counterbalance mass whereby said virtual image of said linear array is swept by the motion of said mirror to produce a raster display, said first and second reaction forces substantially cancelling each other at said base. - View Dependent Claims (16, 17, 18, 19, 20)
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21. A miniature optical display device for generating a raster image to display selected information, said display device comprising:
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a linear array of light-emitting devices; a mirror; an optical system located between said linear array and said mirror, said optical system projecting a virtual image of said linear array via said mirror; a base; - View Dependent Claims (22, 23)
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24. In a miniature display apparatus which generates a raster image from a linear array of light-emitting devices, said display apparatus having a base, a mirror, a first spring connecting said mirror to said base at a first point and a driving mechanism for oscillating said mirror relative to said base, the reaction force generated by the motion of said mirror being transmitted through said spring to said base, a method for reducing the vibration of said base due to said reaction force, said method comprising the steps of:
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A. mounting a counterbalance mass on said base by means of a second spring attached to said base at a second point, a mechanical resonant frequency of a mirror/first spring system being substantially equal to a mechanical resonant frequency of a counterbalance mass/second spring system; B. providing a driving mechanism to oscillate said counterbalance mass, the reaction force produced by the oscillation of said counterbalance mass being conducted through said second spring to said base, and C. positioning said first point relative to said second point so that the reaction force of said mirror is substantially cancelled by the reaction force of said counterbalance mass.
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25. A miniature optical display device for generating a raster image to display selected information, said display device comprising:
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an array of light-emitting devices; a mirror; an optical system located between said array and said mirror, said optical system projecting a virtual image of said array via said mirror; a base; first spring means connecting said mirror to said base so as to allow said mirror to oscillate relative to said base; and driving motor means for imparting an oscillating motion to said mirror so that said mirror pivots about a point located along said spring means between said mirror and said base whereby said virtual image of said array is swept by the motion of said mirror to produce a raster display. - View Dependent Claims (26)
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Specification